Along with technical developments, flat panel display devices have substituted bulky CRT display devices and become current mainstream display devices. Currently, common flat panel display devices comprise an LCD (Liquid Crystal Display) and an OLED (Organic Light-Emitting Diode) display device.
The liquid crystal display device comprises an array substrate and a color filter substrate between which liquid crystals are filled. A thin film transistor (TFT) is disposed on the array substrate, and is a control member as to whether light can be emitted out of the display device, and the TFT comprises a plurality of layer structures such as a gate layer, a gate insulating layer, an active layer, a passivation layer and a source/drain layer; a color filter layer (also called a color filter sheet) is disposed on the color filter substrate, and the color filter layer is a key member as to whether the display device can be colorized and comprises a plurality of color sub-layers such as red, green and blue. The white light emitted from a backlight passes through the color filter layer and generates three primary colors of red, green and blue respectively by way of the color resist of the color filter layer; meanwhile, a thin film transistor array is used to adjust the voltage loaded on the electrodes, such that liquid crystal molecules are deflected to control the passage of the light, change the proportion of the three primary colors, and finally achieve the color display of images. During manufacturing the liquid crystal display device, usually the color filter substrate and the array substrate are manufactured respectively, and then the color filter substrate and the array substrate are assembled and packaged together. In order to ensure the normal operation of the liquid crystal panel, it requires a high precision on the alignment and assembling of the array substrate and the color filter substrate.
The OLED is a light emitting device using an organic solid semiconductor as a light emitting material, and the OLED display device is a display device using the OLED to realize image display. Wherein, the technology of a white OLED (i.e., WOLED) is especially mature and has good stability and a simple manufacturing process, thus is widely used in display devices. Being the same with the liquid crystal display device, the WOLED display device uses the color filter layer to realize colorization.
In the liquid crystal display device or the WOLED display device, each externally visible minimum pixel point (i.e., “visible pixel”) is constituted by a plurality of pixel units, and each of the pixel units has different colors of color filter layers, thus the light which passes through different pixel units is changed into different colors after passing through the color filter layer, and the different colors of light are mixed to be the light emitted from the “visible pixel”.
Along with the development of display technologies, currently, a mode that the color filter layer is disposed on the array substrate (Color Filter on Array, COA for short) to achieve color display appears in the WOLED display device. As illustrated in FIGS. 1A and 1B, on the array substrate already formed with a thin film transistor main body layer 2 (comprising a gate layer 21, a gate insulating layer 22, an active layer 23, a source/drain layer 24 and a passivation layer 25 (PVX for short)), a color filter layer 5 is formed on the passivation layer 25 using a photoetching process (comprising a plurality of steps such as coating, exposing and developing), as illustrated in FIG. 1A; and then a flat protective layer 4 is formed on the color filter layer 5, and finally a pixel electrode via hole 6 is formed, as illustrated in FIG. 1B. Using this mode can save the separate manufacturing of the color filter substrate, and the precision on the alignment and assembling of the color filter substrate and the array substrate need not be considered; and the manufactured array substrate has good stability, thus it is currently a common method to achieve the full color of the WOLED display device. However, as illustrated in FIG. 1, the passivation layer 25 of the thin film transistor main body layer further comprises the pixel electrode via hole 6 (Via Hole), the pixel electrode via hole 6 is firstly formed above the thin film transistor main body layer 2, and when the photoetching process is adopted to form the color filter layer 5, the step of coating the photoresist material and the metal ions, water molecules and etc. in the developer adopted in the developing step in the photoetching process affect the characteristics of the thin film transistor; also, a color filter layer 5 is first formed on the thin film transistor main body layer 2, and when the pixel electrode via holes 6 are etched in the passivation layer 25, the acid substance and etc. in an etching liquid affect the characteristics of the color filter layer 5.
During manufacturing the liquid crystal display device, although the color filter layer can be formed on the array substrate referring to the COA mode by which the WOLED display device achieves color display, according to the method of adopting the photoetching process to form the color filter layer in the prior art, the problem of affecting the characteristics of the thin film transistor will inevitably appear.